The American Automobile Industry in World War Two
An American Auto Industry Heritage Tribute
By David D Jackson

Overview      The U.S. Auto Industry at the Normandy Invasion, June 6, 1944    The U.S. Auto Industry and the B-29 Bomber   U.S. Auto Industry Army-Navy "E" Award Winners   The Complete listing of All Army-Navy "E" Award Winners   Sherman Tanks of the American Auto Industry   Tank Destroyers of the American Auto Industry    M26 Pershing Tanks of the American Auto Industry   Serial Numbers for WWII Tanks built by the American Auto Industry

    Automobile Manufacturers:  American Bantam Car Company   Checker   Chrysler   Crosley   Ford   General Motors   Graham-Paige   Hudson
   Nash-Kelvinator   Packard      Studebaker    Willys-Overland

General Motors Divisions
(Undergoing development) Aeroproducts   Brown-Lipe-Chapin   Buick   Cadillac   Chevrolet   Cleveland Diesel   Delco Appliance   Delco Products   Delco Radio   Delco-Remy   Detroit Diesel   Detroit Transmission   Electro-Motive   Fisher Body   Frigidaire   GM Proving Grounds   GM of Canada   GMC   GMI   Guide Lamp   Harrison Radiator   Hyatt Bearings   Inland   Moraine Products   New Departure   Oldsmobile   Packard Electric   Pontiac   Saginaw Malleable Iron   Saginaw Steering Gear   Southern California Division   Rochester Products   United Motors Service

Truck and Implement Manufacturers:   American LaFrance   Autocar  Diamond T   Caterpillar   Clark Equipment Company   Cleveland Tractor Company   Federal Motor Truck   International Harvester    Mack Truck
   Marmon-Herrington Company   Massey-Harris   Pacific Car and Foundry  Reo Motor Car Company   R.G. LeTourneau   Seagrave Fire Apparatus   Ward LaFrance Truck Corporation   White Motor Company

Automotive Tire
   B.F. Goodrich    Firestone Tire and Rubber Company
 Updates and Additions  


Torqmatic 900-T Hellcat Transmission
Detroit Transmission (Hydra-Matic) Division of General Motors Corporation in World War Two / WWII
Detroit, MI
1939-1962 as Detroit Transmission Division
1962-1990 as Hydra-Matic Division
Combined with GM engine Divisions as Powertrain in 1990

This page updated 12-27-2016.

Abstract:  Even though Detroit Transmission developed what became one of GM's most recognizable products in the Hydra-Matic and later Turbo Hydra-Matic transmission, its name has been lost to history.  In 1962 the name of the Division changed to Hydra-Matic, which is the name most persons familiar with the auto industry recognize. In 1990 Hydra-Matic was absorbed into GM Powertrain and was no longer an independent Division of GM.  During WWII Detroit Transmission developed Hydra-Matic and Torqmatic transmissions that introduced the automatic transmission to American tanks.  Tank automatic transmissions designed by GM Research and Detroit Transmission Division late in WWII have been standard equipment on American tanks ever since the end of the war.

The complete story is below, including Detroit Transmission's 1944 wartime era booklet entitled "Teamwork in Peace and War".

A state of the art WWII technology leader?  It may be hard to believe 70 years later that the M5 light tank, like this forlorn example in downtown Hartford City, IN, was a technology leader in WWII.  While the 37mm gun was insufficient to destroy another tank, and its armor plate too thin to protect the crew against German tank guns, its Hydra-Matic transmission was state of the art.  Every tank or tank destroyer built for the US military after the M5, including the M1 Abrams, had an automatic transmission.  Detroit Transmission is responsible for this technical revolution, starting with the early technology of the Hydra-Matic and Torqmatic transmissions.  Author's photo

How the Hydra-Matic came to be named

When Detroit Transmission was created, the Hydra-Matic transmission had not yet been developed, and it had not yet been named.  When the development of the transmission utilized the hydraulic fluid that was in the hydraulic coupling to also flow through the body and valves of the transmission itself, it was named Hydra-Matic.  This stood for the hydraulic fluid that flowed through it, and for the fact that it now automatically shifted through the gears without any assistance from the driver.

A General History of Detroit Transmission Division

Detroit Transmission Division of General Motors began in 1939 for the production of the new shiftless transmission now known as Hydra-Matic for introduction in the 1940 Oldsmobile.  The following year, Cadillac introduced it on its vehicles.  When automobile production stopped in February of 1942 for the duration of World War Two, 200,000 transmissions had been shipped to Olds and Cadillac.  During the war Hydra-Matics were used in various tanks and armored vehicles.  It continued to increase sales after the war, as drivers switched from manual shifting to the ease of automatic shifting.  On September 22nd, 1947 Detroit Transmission shipped its 500,000th Hydra-Matic. 

This 1940 Oldsmobile chassis and drive train is on display at the Ypsilanti Automobile Heritage Museum in Ypsilanti, MI.  The significance of this 1940 Olds is that it was part of the first year introduction of the Hydra-Matic transmission, the first fully automatic transmission to be offered for sale.  Author's photo.

The development of the automatic transmission prompted the forming of the Detroit Transmission Division by GM management to manufacture the units.  Author's photo.

General Motors policy was, and still may be, for one car division to introduce a new product for sale rather than all of them.  This allows the corporation to monitor acceptance by the public, and confine any issues that arise to one particular division.  In the case of the Hydra-Matic, the rough shifting issues did not prevent excellent acceptance by the public, and the introduction of the product at Cadillac for the 1941 model year.  Author's photo at the Ypsilanti Automobile Heritage Museum.

The Detroit Transmission Plant moved into this existing six story factory on Riopelle Street in Detroit, MI on May 15, 1939.  Originally the Division occupied 99,416 square feet on the bottom three floors.  It moved to the fourth floor at the end of 1940; and into the fifth floor in 1941.  This gave the Division a total of 275,698 square feet.  By March 1943 all six floors were in use and floor space was at 623,403 square feet; dedicated to the manufacture of the Hydra-Matic transmission.  When Torqmatic went into production, manufacturing was set up in a building across the street.

The Livonia Plant Fire

After WWII the Division moved from its original location on Riopelle Street in Detroit to a 34.5 acre plant in Livonia, MI.  The Livonia plant was the scene of the August 12th, 1953 fire that destroyed the plant and shut down production of Hydra-Matics for twelve weeks.  Not only were Cadillac and Oldsmobile Divisions affected but Pontiac, Nash, Hudson, Kaiser and Lincoln were also offering the Hydra-Matic as an option on their vehicles   During this period new equipment was made by all GM divisions, which had all tool rooms working seven days a week, twelve hours a day.  Simultaneously, Detroit Transmission moved into the former Ford Willow Run bomber plant, and made Hydra-Matics there until it was vacated by GM in 2010 during the Great US Automobile Industry Meltdown.

When I went worked Plant Protection for Lansing Fisher Body on  while working my way through college in the late sixties, the Detroit Transmission Division fire was still discussed.  This event dictated much of what we did at Fisher Body.  As a result of the fire, which was started by sparks from a welder igniting nearby flammable liquids, GM implemented standard policy which still requires on-location approval by a Plant Protection fire inspector before any welding or cutting is done.  Fire prevention within GM was driven by the Livonia fire.  When I arrived at Delco-Remy and became a supervisor in one of many tool rooms, I heard stories from the "old timers" about working 7 days a week, 12 hours a day remaking the tooling to restart Hydra-Matic production.  All GM tool rooms were involved in this massive tooling endeavor. 

An aerial photo of the infamous Detroit Transmission fire in Livonia, MI on August 12, 1953.

In 1962 Detroit Transmission Division became the Hydra-Matic Division of GM.

Besides making millions of transmissions,  Hydra-Matic built 469,217 M16A1 rifles that the military desperately needed for the Vietnam war.  The author's M16A1, that he was issued by the Michigan National Guard in 1971, was built by Hydra-Matic.  Author's photo added 12-24-2015.

In 1990 Hydra-Matic Division of GM, as it was then known, was merged into GM Powertrain and lost its individuality and identity.

World War Two 

Detroit Transmission won the Army-Navy "E" for Excellence Award on June 22, 1944.  It then added a star six months later.
 This was earned for the always meeting schedule for its Hydra-Matic and Torqmatic transmissions utilized in US Army tanks and tank destroyers.

Detroit Transmission Division World War Two / WWII Production Numbers / Statistics: Detroit Transmission Division of GM produced 54,991 Hydra-Matic and Torqmatic transmissions for tanks, tank destroyers, and armored cars during World War Two.  The Division also produced Browning machine guns parts for the 1,218,837 weapons that four other GM divisions built during the war.

The Hydra-Matic Transmission in World War Two: The Detroit Transmission Hydra-Matic was the most utilized automatic transmission in armored vehicles during WWII.  Along with the Detroit Transmission Torqmatic also used in armored vehicles, they were the only two of their type used.  The Hydra-Matic was also the first of its type to be used by the military in tanks and armored cars.

Initial use of a Detroit Transmission Division was on May 29, 1939 when a Detroit Diesel Division powered M2 tank had a heavy duty four speed transmission installed in it.  This was the first time an automatic transmission was installed in a tank.  The advantages were immediately clear to the military ordnance officers:  elimination of engine stalling as the fluid coupler did not mechanically lock up the engine to the transmission, full power could used under all conditions, elimination of the heavy shift lever, best of all, the elimination of the clutch and the double clutching required every time the driver had to change gears.  By eliminating the clutch and manual shifting of gears, the driver was able to concentrate on looking where the tank was going and not being distracted with manipulating the gears and clutch.

Manual transmissions in tanks also had the severe disadvantage of slowing down on the battlefield when changing gears, making them easier targets to be hit by enemy fire.  The new automatic transmission eliminated this tactical disadvantage. 

In February 1941 a newer, heavier duty five speed transmission was installed in the M2 tank, which was now heavier with added armor and weapons.  The one engine was having problems moving the tank.  According to page 18 in "Teamwork in Peace and War", it was Detroit Transmission engineers that suggested the use of two Cadillac V-8 engines matched with two Hydra-Matic transmissions that resulted in the M5 Stuart tank.

If one refers to "Cadillac...From Peace to War" on the Cadillac page of this website, that Division notes that it broached the subject of a new light tank with two of its engines and Hydra-Matic transmissions to Army Ordnance.  Which version is correct?  Most likely both, as no doubt both Divisions were working with the Ordnance Department on projects to improve the tank by the use of their products.

The first run of the new M5 Stuart tank with the new Hydra-Matic 250-T transmission took place on September 17, 1941 at the General Motors Proving Grounds in Milford, MI.  Next the new tank went on a 560 cross country trip on public roads from Detroit to the Aberdeen Proving Grounds in Maryland.  Drivers on the trip were able to easily negotiate the hills of Pittsburgh in with no driver fatigue.  The dawn of a new era of tanks transmissions had arrived.  After more successful testing at the Aberdeen Proving Grounds the Army ordered the first 266 M5 Stuarts, the first of 1,824 M5s and a total of 24,941 light tanks, armored cars and landing vehicle tanks equipped with the Hydra-Matic transmission during WWII.

An aside:  One can only wonder what civilians thought of the M5 as it drove through cities and towns across the eastern US in late 1941.  The author remembers a similar type incident in the Castleton area of Indianapolis after 9-11-2001.  Allison Transmission was doing engineering development on a GM of Canada LAV, and took it out on the local streets for a test run.  Paranoid civilians thought the country was under attack because one armored vehicle was driving around and called the police.  Needless to say, Allison did not do any more road tests in the area.  Were the civilians in 1941 were as paranoid as those in 2002?

For the complete inside story of the development of the Hydra-Matic not only military use in WWII, the the early work for Oldsmobile and Cadillac, please read pages 1 through 25 of "Teamwork in Peace and War" at the bottom of this page. 

The Torqmatic Transmission in World War Two:
It should be noted that current historic literature sometimes spells the transmission name Toquematic.  This is incorrect.  Please see the 1944 Detroit Transmission booklet below entitled "Teamwork in Peace and War" for verification of the proper spelling; Torqmatic.

Development of the Torqmatic began in December 1942 and on February 17, 1943 it was placed on a dynameter for testing.  More testing then took place on several different heavy vehicles at the Milford Proving Ground. 

The Torqmatic transmission was similar to the Hydra-Matic with the exception that it used a "Hydraulic Torque Converter" instead of the fluid coupling used in the Hydra-Matic.  While similar in function, the torque converter has a stator that decreases slippage at low rpms, just what was needed to get tanks moving from a stop in a hurry.  This was the first application of a torque converter in an automatic transmission.  After World War Two, Detroit Transmission would incorporate the more costly and complex technology into its Hydra-Matics, and the term Torqmatic would disappear from use.  But the torque converter has been a staple of automatic transmissions for 50 years.

Detroit Transmission opened a second plant across the street from its original facility for the manufacture of the Torqmatic transmission, which was used in 2,507 Buick built M18 Hellcat tank destroyers.  This had three forward gears and one for reverse.  It was mated to a Continental R-976-C2 nine cylinder radial aircraft engine that produced 400 hp at 2,400 rpms.  This was four times the horsepower that the Hydra-Matic 250-T saw in the Cadillac V-8 engine.  Not only was this the first use of the Detroit Transmission Torqmatic transmission, it was the first use of a torque converter and the matching of an automatic transmission to an aircraft radial engine. 

The second and final Torqmatic transmission went into the T26E3/M26 Pershing built at the end of the war.  The Perishing was powered by 500hp Ford V-8 engine, which was 20% more horsepower than the radial engine in the 18 ton M18 Hellcat.  The M26 Pershing weighed in at 46 tons.  Therefore the Torqmatic for this tank had to be considerably larger and more capable than the one for the Hellcat.  The Torqmatic with very little slippage at low rpms was key to getting and keeping the heavy tank moving with what was found to be an underpowered engine for its weight.

The first application of the Torqmatic.  The M18 Hellcat tank destroyer matched the Detroit Transmission Torqmatic automatic three forward speed transmission with an R-975 radial aircraft engine that produced up to 400 hp.  This was four times the horsepower of the Cadillac V-8, resulting in the need for a much more capable transmission than the Hydra-Matic 250-T for the M5.  This was also the only time an automatic transmission was matched with an aircraft radial engine.  This M18 Hellcat is at the Ropkey Armor Museum.  Author's photo added 12-27-2016.

Looking through the driver's hatch the Detroit Transmission Division of GM Torqmatic automatic transmission is viewable.  The Buick M18 was the only tank destroyer to have an automatic transmission.  Author's photo added 12-27-2016.

Here the gearshift handle is viewable along with the gear indication on top of the transmission.  On the floor there are only the accelerator and brake pedals.  A clutch pedal is not needed with the automatic transmission.  Author's photo.Author's photo added 12-27-2016.

 Author's photo added 12-27-2016.

This view through the open assistant driver's hatch lets one look at the Detroit Transmission Division of GM built Torqmatic transmission.  The M18 and the M24 were the last American tank destroyers or tanks to have power applied to the front of the tracks, and have the transmission located between the driver and assistant driver.  Author's photo added 12-25-2015.

Detroit Transmission Division of GM World War Two Applications

Application Quantity Model  Transmissions per application Total Transmissions
 M5 Stuart tanks (1,824) Hydra-Matic 250-T 2 (3,648)
 M5A1 Stuart tanks (6,800) Hydra-Matic 250-T 2 (13,600)
 M8 3 inch howitzer motor carriages (1,778) Hydra-Matic 250-T 2 (3,556)
 M24 Chaffee tanks (4,731) Hydra-Matic 250-T 2 (9,462)
 Staghound Armored Cars (3,844) Hydra-Matic T-17


2 (7,688)
 LVT(3)s (5,924) Hydra-Matic 250-T 2 (11,848)
Mark 1 Armored Snowmobile (410) Hydra-Matic 250-T 1 (410)
 T18E2 Boarhounds (30) Hydra-Matic 2 (60)
Total Hydra-Matics (24,931)     (50,272)
 M18 Tank Destroyers (2,507) Torqmatic 1 (2,507)
M26 Pershing tanks (2,212) Torqmatic 1 (2,212)
Total Torqmatics (4,719)     (4,719)
Grand Total (29,650)     (54,991)

The Legacy of the Detroit Transmission Hydra-Matic and Torqmatic Tank Transmissions: During the later part of WWII, Army Ordnance, GM Research, and Detroit Transmission developed Cross Drive Transmission which was completed in 1945.  The transmission was designated the CD-850, and Allison built it in Indianapolis, IN after the war for use in the M46, M47, M48, and M60 tanks.  Allison then developed the next generation tank transmission that is currently used in the M1 Abrams main battle tank.  

In 1946 General Motors made an internal technology transfer.  Allison Division of General Motors, which had exclusively produced inline aircraft engines, such as the V-1710 used in the P-38 Lightning, was tasked by the Corporation with making heavy duty transmissions for not only tanks, but commercial vehicles such as trucks and buses.  Detroit Transmission was then allowed to focus on the larger market of automotive passenger car applications using the trade name Hydra-Matic. 

Today Allison no longer produces aircraft engines as that product line was purchased by Rolls-Royce.  Allison Transmission is also no longer part of General Motors, but is the largest producer of heavy duty transmissions in the world.  Since Allison Transmissions took over the heavy duty transmission business in 1946, its transmission for trucks and buses carry the trade name Torqmatic.

Unfortunately, Allison Transmission does not acknowledge the pioneering engineering work done by Detroit Transmission and others during WWII previous to the 1946 technology transfer.  In its history portion of its website it shows in 1946 it developed the CD-850 tank transmission.  Technology this complicated just did not appear out of thin air as is implied on the website.  It is unfortunate that Allison does not acknowledge where the technology came from with its roots in the Detroit Transmission Division and World War Two tanks.

The Legacy of the Assistant Driver in American tanks:  All tanks during WWII had an assistant driver, who had the important task of watching where the tank or tank destroyer was going while the driver was distracted while shifting gears and double clutching.  This was the case for the M3, M4, M10, and M36, but not for the tanks and tank destroyers with either Hydra-Matic or Torqmatic automatic transmission supplied by Detroit Transmission.  In these vehicles the assistant driver no longer needed to watch the road because with the gears shifting automatically, and no clutch, the driver could now focus on the road ahead.  However, Army Ordnance tank designers did not realize this until after WWII, when the M41 Walker Bulldog and the M48 Patton tanks and finally eliminated the assistant driver.

This World War Two Hydra-Matic 250-T Transmission can be seen at the Ropkey Armor Museum in Crawfordsville, IN.  The transmission is attached to a Cadillac V-8 and would have seen applications in the M5 series tanks, M8 motor gun carriages, and the LVT(3).  Author's photo.

 Note that not only does it say Hydra-Matic on the case, it also says Detroit Transmission Division on it.  One person on the internet stated irrevocably in an email chain that Detroit Transmission never existed.  Just another case of someone thinking they were an expert on something about which they know nothing.   Author's photo.

This photo shows Cadillac a V-8 attached to the Hydra-Matic transmission.  Author's photo.

Two Detroit Transmission Hydra-Matics each were used in M5 Stuart tanks like this one seen at the 2013 Thunder over Michigan Airshow.  Author's photo.

This photo shows a Detroit Transmission Hydra-Matic transmission being installed along with the Cadillac V-8 into an M5 Stuart tank.  Photo added 2-19-2015.

This M24 Chaffee tank seen at Ropkey Armor Museum also has two 250-T Hydra-Matics in it.  Author's photo.

Here can be seen rows of Detroit Transmission Hydra-Matics mated to GMC 270 cubic inch engines that are awaiting installation into Chevrolet Staghound armored cars.  Photo courtesy of the Military History Institute in Carlisle, PA.

This Staghound (T17E1) with two Hydra-Matic transmissions was photographed at the GM Milford Proving Grounds in June of 1943.

The Hydra-Matic transmission was also used in (410) Mark 1 armored snowmobiles built by Bombardier of Canada.  Three hundred and ninety six of the Mark 1s went to Great Britain with a few of them making it to the Italian Campaign.  Three of them went to Russia.  Photo added 1-19-2016.

This rare photo of the Mark 1 Armored Snowmobile is one of the three that ended up with the Russian Army.  The photo shows the normal armament of a Bren Gun which could be mounted on the side as shown here or in the front.  Photo added 1-19-2016. 

Borg-Warner built 5,924 LVT(3)s like this one seen at the National Military History Center in Auburn, IN.  Each one had two Detroit Transmission Hydra-Matics in it.  Author's photo.

Looking into the landing craft from the rear ramp area one can see the engine and transmission covers have been removed on each side.  Author's photo.

This photo shows the Hydra-Matic transmission connected to the Cadillac V-8 on the right or starboard side of the LVT(3).  Author's photo.

 Author's photo.

 Here one can actually see the Hydramatic embossed in the casting.  Author's photo.

 The left or port side engine/transmission bay.  Author's photo.

 The Hydra-Matic on the port side had a coating of dirt and oil on it.  Author's photo.

This T18E2 GMC built Boarhound used two Hydra-Matic transmissions and was photographed at the GM Proving Grounds on January 19, 1943.

The 46 ton M26 Pershing was the second and final application for the Torqmatic as produced during WWII by the Detroit Transmission Division of GM.  The M26 was the first "modern" tank from which all future American tanks would take their design cues from.  A low profile, adequate armor and main gun, torsion bar suspension, rear drive, and an automatic transmission made this the first modern American tank.   Author's photo taken at Fort Jackson, SC.

The M-26 Pershing Torqmatic transmission had three forward speeds and one reverse.  First gear was a 1:1 ratio, second gear 1:2.337 ratio and third gear 1:4.105 ratio.  When in first the M26 had a speed of 0-9mph, in second 6-19mph and in third its speed range was 12-20 mph.  The reverse ratio was 1:1.322 with speed of 0-9mph. Photo from "TM 9-1735A Ordnance Maintenance--Medium Tanks M26 and M45, Power Train".   The M45 was the 105mm Howitzer version.  Chrysler built 185 of the M45s late in WWII.

The next two pages are from my page "One Million Browning Machine Guns" located on the main GM page.  Note above that Detroit Transmission is listed as one of four GM divisions that manufactured some of the 270 parts that went into a .50 cal Browning and 159 parts that made up the .30 cal Browning machine gun.  Photo added 2-19-2015.

Detroit Transmission manufactured parts went to the weapons shown above.  Photo added 2-19-2015.

Teamwork in Peace and War
This 1944 publication tells the story of the early history of the Hydra-Matic Transmission as developed for use on 1940 Oldsmobiles and 1941 Cadillacs, the Hydra-Matics introduction to the M5 Stuart Tank, and the Torqmatic transmission's development for the M18 Hellcat Tank Destroyer.

This gives an excellent insight into how the Hydra-Matic and Torqmatic transmissions were introduced into World War Two combat vehicles.

This page and the next two pages describe the first time a tank was driven with an automatic transmission and its advantages over a manual transmission.

The next four pages describe how the Hydra-Matic transmission along with the Cadillac V-8 engine were mated together in the M5 Stuart light tank.

This page describes the successful 560 mile road trip the first M5 tank equipped with a Hydra-Matic transmission made between Detroit, MI and Aberdeen, MD and how well it perfomed.

This page tells how the name "Hydra-Matic" came into being.

The next four pages describe how Hydra-Matic transmissions were developed for use in he M5.

The next five pages describe how Detroit Transmission tooled up to produce the 250-T Hydra-Matic Transmission for World War Two.

These two pages describe the Torqmatic transmission as built by the Detroit Transmission Division.

On June 22, 1944 the Detroit Transmission Division was awarded the prestigious Army-Navy "E" for Excellence Award.

 Link to:  Torqmatic 900-T Hellcat Transmission




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